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31 Cards in this Set
- Front
- Back
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Who proposed the Continental Drift Hypothesis?
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It was discovered by Alfred Weneger in 1912.
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What does the Continental Drift Hypothesis state?
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It says the the 7 continents were once Pangaea and were surrounded Panthallassa. 250 million years ago it broke apart.
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Pangaea
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The land mass that the earth was once in. It means "all lands".
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Panthallassa
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The ocean that surrounded the land mass that was once earth.
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What evidence was given to support the Continental Drift Hypothesis?
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Fossil, rock deposits, glacial evidence, the continents, and climate
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Fossil evidence?
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Fossils more than 200-250 million years old on different continents were identical but, younger fossils differed.
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Rock evidence?
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Rock deposits on different continents were the same and type.
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Glacial evidence?
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Striation patterns match-up on different continents. If you were to put them together they make a consistent pattern.
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Climate evidence?
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On different continents there are things that seem unlikely to be there. (Ferns in Antarctica and glaciated rocks and Africa.)
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What was the problem with the hypothesis?
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Weneger could not explain how the continents moved. He did not know about Paleomagnetic studies.
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Who proposed the Continental Drift Hypothesis?
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It was discovered by Alfred Weneger in 1912.
|
|
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What does the Continental Drift Hypothesis state?
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It says the the 7 continents were once Pangaea and were surrounded Panthallassa. 250 million years ago it broke apart.
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Pangaea
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The land mass that the earth was once in. It means "all lands".
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Panthallassa
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The ocean that surrounded the land mass that was once earth.
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What evidence was given to support the Continental Drift Hypothesis?
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Fossil, rock deposits, glacial evidence, the continents, and climate
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Fossil evidence?
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Fossils more than 200-250 million years old on different continents were identical but, younger fossils differed.
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Rock evidence?
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Rock deposits on different continents were the same and type.
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Glacial evidence?
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Striation patterns match-up on different continents. If you were to put them together they make a consistent pattern.
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Climate evidence?
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On different continents there are things that seem unlikely to be there. (Ferns in Antarctica and glaciated rocks and Africa.)
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What was the problem with the hypothesis?
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Weneger could not explain how the continents moved. He did not know about Paleomagnetic studies.
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Mantle convection
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People realized that heat did not rise the same way from different parts of the earth. In some places it gets hot and rises and in some it gets cool and sinks. The outer core is the source for it and may change the direction for it.
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Convection in ridges?
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Areas of high heat flow and volcanic activity. The sea floor was younger based on thickness of sediment.
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What did Harry Hess do?
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He realized that the ocean floor and continental crust are linked as two.
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What about ocean rocks?
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They are much younger than continental rocks.
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What was discovered in 1947?
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Hot material rises at oceanic ridges. Explains high heat flow, basaltic volcanic activity, and why ocean floor ridges are bulged. Where land and the ocean meet at trenches, ocean crust sinks at the same rate it rises. Sea floor crust is younger at ridges then get progressively older. The sea floor is not flat and the sediment layers are a lot thinner than expected.
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Who proposed the hypothesis of sea floor spreading?
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Robert Dietz in 1947.
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What do scientist believe causes the reversal of earth's magnetosphere?
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The outer core
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Normal Polarity?
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When magnetic minerals in newly formed rocks point themselves north.
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Reversed Polarity!?
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When magnetic minerals in newly formed rocks point themselves south.
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What did scientists find out about polarity?
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They found that the Mid-Atlantic Ridge had show parallel magnetic 'stripes' that were that were symmetrical to the 'stripes' on the other side of it.
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What else did scientist find out about polarity?
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They found that the ocean crust of a certain age had normal polarity. Scientists working on continental rock found the same thing! Vine and Matthews found that magnetic stripes are products of steady creation of new ocean crust over time. This supported the theory of Hess.
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